Pulm Flashcards
What’s the earliest a pre-mature baby can survive?
25-26 weeks. By this point, the alveoli have developed so gas exchange (breathing) is possible.
What does atalectasis mean?
Collapsing of the alveoli
What is aspiration?
When food or vomit gets into the airways
What’s more anterior- the trachea or the esophagus?
The trachea
What are causes (3) of hypercapnia?
Hypercapnia= high CO2 in the blood. Causes:
- Fever (increased metabolic activity)
- Hypoventilation (blowing off less CO2)
- Dead space (ventilation w/o perfusion. There is a blood flow problem, so CO2 is remaining in the blood rather than getting pushed into alveoli)
Does shunting (perfusion w/o ventilation) lead to hypercapnia (inc CO2)? Explain.
No. You have a ventilation problem but blood will shunt to the alveoli that are working and shunted away from the alveoli that are not working/ not ventilating/ not capable of gas exchange. So CO2 will not build up. *you will get inc CO2 in the case of dead space where you have a blood flow problem that prevents the CO2 in blood from getting pushed up into the alveoli
What is dyspnea?
Shortness of breath (SOB)
When does lung development begin in embryo?
Week 4
What structure do the lungs develop from in embryo?
The lung bud (“respiratory diverticulum”)= outgrowth of the GI tract (specifically the foregut, or future esophagus)
Explain the main events in each stage of lung development: (1) embryonic (weeks 4-7), (2) pseudoglandular (weeks 5-17), (3) canalicular (weeks 16-25), (4) saccular (week 26-birth), and (5) alveolar (week 36-8 years).
(1) embryonic (weeks 4-7): lung bud branches down to tertiary bronchi
(2) pseudoglandular (weeks 5-17): there’s branching all the way down to terminal bronchioles (lungs resemble a gland)
(3) canalicular (weeks 16-25): terminal bronchioles further branch into respiratory bronchioles and alveoli w/ lots of capillaries. Pneumocytes develop at 20 weeks (type II pneumocytes make surfactant).
(4) saccular (week 26-birth): alveoli further develop and form sacs (seperated by septae)
(5) alveolar (week 36-8 years): “alverolarization” (alveoli get subdivided by septa walls so that they are smaller but there’s triple the amount—> inc surface area)
What is oligohydramnios? Why is this a problem for lung development?
Decreased amniotic fluid (from fetal kidney problem—> dec urine= dec amniotic fluid production) (part of Potter sequence). The baby in embryo needs to swallow amniotic fluid to expand their developing lungs. Amniotic fluid fills baby’s lungs and stimulates further development of the lungs. W/o enough amniotic fluid, the baby is born with PULMONARY HYPOPLASIA= underdeveloped lungs.
What is pulmonary hypoplasia?
Underdeveloped lungs. Associated with congenital diaphragmatic hernia (pleuroperitoneal membrane not formed properly—> hole in diaphragm—> abdominal organs herniate into chest and prevent proper lung development) and bilateral renal agenesis (fetal kidney problem—> lack of urine= lack of amniotic fluid—> lungs aren’t stimulated to develop fully)
What are bronchogenic cysts?
Abnormal budding of the foregut and dilation of terminal/ large bronchi. Cysts are fluid filled, lined by respiratory epithelium, contain cartilage
What is bronchopulnoary dysplasia?
Lung disease that affects premature babies. Caused by damage from mechanical ventilation (O2 toxicity, lung trauma)—> alveolarization (alveoli subdividing so you have more, smaller alveoli= inc SA) doesn’t progress normally—> respiratory problems during infancy (but often improves in childhood as lungs continue to develop).
What are club cells?
Non-ciliated cells in bronchioles (beginning of respiratory zone). Secrete a component of surfactant and do detoxification.
Describe type I and type II pneumocytes (alveoli cells).
TYPE I: makes up 97% of your alveolar cells. Line the alveoli. Squamous and thin for optimal gas exchange.
TYPE II: secrete surfactant to dec surface tension and prevent alveolar collapse. Cuboidal. Also can proliferate into other cells during lung damage to help heal the lungs.
What ingredients is surfactant made of?
Lecithins. The most important one is DPPC (dipalmitoylphosphatidylocholine)
During what week of development does surfactant start getting made?
Week 26
What is neonatal respiratory distress syndrome (NRDS)? What are 3 risk factors?
Surfactant deficiency (breathing disorder from immature lungs). Risk factors: premature baby, maternal diabetes (insulin dec surfactant production) C-section delivery (cortisol inc surfactant production and C-sections= less stressful delivery= less cortisol= less surfactant production).
What test can we do to screen for fetal lung maturity?
Lecithin-sphingomyelin. Lecithin (what surfactant is made of) should shoot up late in pregnancy when the baby lungs mature. A ratio of >2 is healthy. If <1.5 that’s predictive of NRDS (neonatal respiratory distress syndrome= surfactant deficiency= baby born with immature lungs and will need help breathing for a while)
Starting with the trachea, name all the respiratory tract anatomical structures in order.
Trachea—> primary bronchus—> secondary bronchus—> tertiary bronchus—> bronchioles—> terminal bronchioles (end of conducting zone)—> (start of respiratory zone) respiratory bronchioles—> alveoli
What is the general purpose of the conducting zone? Respiratory zone?
Conducting zone: warms, humidifies, and filters air. Respiratory zone: does gas exchange.
What kind of cells secrete mucous as a way of protecting against infection?
Goblet cells in the bronchi.
How many lobes make up the right lung? Left lung?
Right lung: 3 (upper lobe, middle lobe, lower lobe)
Left lung: 2 (upper lobe and lower lobe) heart on this side!
What is the carina?
The point where the trachea branches/ bifrucates into the right and left bronchus
If you aspirate a foreign body, like a peanut, where in the lungs is it most likely to end up—if you were standing up? Laying down?
Most likely to get into the RIGHT lung bc it doesn’t have to take as sharp of a turn going from trachea into right bronchus (as compared to trachea to left bronchus). It will always fall to the lowest point by gravity so…
Standing up—> goes to right lower lobe (inferior part)
Laying down—> goes to right upper or lower lobe (posterior part)
What accessory muscles (muscles other than the diaphragm) are used to breathe during exercise or respiratory distress?
Inspiration—> muscles from the neck (scalenes, SCM)
Expiration—> muscles from the abdomen (rectus muscle, internal and external obliques, transverse abdominis, internal intercostals)
What structures perforate the diaphragm at T8, T10, and T12?
T8: IVC, right phrenic nerve
T10: esophagus, vagus nerve/ CN 10
T12: aorta (red), thoracic duct (white), and azygos vein (blue) (“at T-1-2 it’s red, white, and blue”)
“I (IVC) ate (T8) ten (T10) eggs (esophagus) at (aorta) noon (T12)”
What nerve innervates the diaphragm and what spinal levels does it stem from?
Phrenic nerve. C3, C4, C5 keeps the diaphragm alive!
What is inspiratory reserve volume (IRV)?
The extra volume of air you can breathe in beyond normal inspiration
What is tidal volume (TV, or Vt)?
The volume of air you normally breathe in/ out (with each quiet inspiration, typically 500mL)
What is expiratory reserve volume (ERV)?
Extra volume of air you can breathe out beyond normal expiration
What is residual volume (RV)? Can you use spirometry to determine it?
The volume of air that stays in your lungs after you breathe out (no matter how hard you blow out). NO! Spirometry can only measure what you CAN blow out into the machine.
What is inspiratory capacity?
The full capacity you can breathe in
IRV + TV (inspiratory reserve vol, or the extra vol you can breathe in + tidal volume, or the normal vol you breathe)
What is functional residual capacity (FRC)?
The volume of air in the lungs after you breathe out
RV + ERV (residual vol, or the vol of air that stays behind in the lungs no matter how hard you blow out + expiratory reserve volume, or the extra vol of air you could breathe out if you blew out harder than normal expiration)
What is vital capacity (VC) also known as forced vital capacity (FVC)?
Max volume of air you can forcibly breathe out after max inspiration
TV + IRV + ERV (tidal volume, or the vol of air you normally breathe + inspiratory reserve volume, or the extra vol of air you can breathe in + expiratory reserve vol, or the extra vol of air you can breathe out)
What is total lung capacity (TLC)?
Vol of air in lungs after max inspiration (the total amount of air that can be in your lungs)
IRV + TV + ERV + RV (sum of all 4 lung volumes)
What is physiological dead space? What’s the difference between anatomic dead space and alveolar (functional) dead space?
In general dead space= air that doesn’t participate in gas exchange.
Physiological dead space= anatomic dead space + alveolar (functional) dead space.
Anatomic dead space= conducting airways (nasal cavity to terminal bronchus) that doesn’t do gas exchange.
Alveolar (functional) dead space= air stuck in alveoli not doing gas exchange bc the alveoli aren’t working well.
Thinking about elastic recoil, what is the tendency of lungs? The chest wall?
Tendency of lungs is to collapse inward. Tendency of chest wall is to spring outward. These forces balance each other.
Describe the structure of adult Hemoglobin (Hb A).
Hb= heme + globin. Heme is made up of iron (Fe) + protoporphyrin. Globin is made up of 2 alpha chains and 2 beta chains.
What is methemoglobin? How do you get this problematic form of Hb? What is the clinical presentation? What is the treatment?
Hemoglobin with Fe3+ (oxidized) instead of Fe2+. Why is this bad? Fe3+ doesn’t bind to oxygen well and you need Hb to bind to oxygen to go deliver it to tissues! And when Fe3+ does bind oxygen, it makes it to where the oxygen cannot be released to tissues.
Get this from nitrites and Benzocaine (med to numb throat before endoscopy).
Present with cyanosis and chocolate colored blood (dark in color bc not getting oxygen).
Treat with methylene blue (and vitamin C).
What is carboxygemoglobin?
Hemoglobin bound to CO (carbon monoxide) instead of oxygen. Bad bc you need Hb to bind oxygen to go deliver it to tissues!
How can you get CO (carbon monoxide) poisoning (leading to carboxyhemoglobin= Hb bound to CO rather than oxygen)?
Forest, car exhaust, gas heaters
How can you get cyanide poisoning?
Inhalation injury (like from fires)
What things shift the oxygen-Hb curve to the right? Explain.
Right shift= inc oxygen unloading to tissues. Remember in terms of exercise: Exercise, inc temp, inc CO2 (from inc tissue metabolism in exercise), dec pH/ inc H+ (think of lactic acid buildup in exercise from metabolism). Also high altitude will shift right (need more delivery of oxygen to tissues since you’re oxygen deprived) and inc 2,3-BPG will shift right (this molecule in RBCs promotes Hb to release oxygen).
What is the Bohr effect?
When you have inc CO2, the Hb-oxygen curve will shift right= more unloading of oxygen to tissues.
**Exercise, inc temp, inc CO2 (from inc tissue metabolism in exercise), dec pH/ inc H+ (think of lactic acid buildup in exercise from metabolism).
In hypoxia, do you have vasodilation or vasoconstriction going on in (1) systemic circulation and (2) pulmonary circulation? Explain.
Systemically you have vasodilation (dec BP, inc blood flow) to inc blood flow and therefore inc the oxygen getting to tissues to compensate for the low oxygen state you are in.
In pulmonary circulation you have the opposite—vasoconstriction (inc BP, dec blood flow). Why? The lungs will shunt blood away from poorly ventilated areas
What’s perfusion-limited? Diffusion-limited?
Perfusion-limited means gas equilibrates/ diffuses before the blood gets there (blood is the “slow guy” limiting the rate of gas exchange).
Diffusion-limited means blood gets there before the gas can equilibrate/ diffuse (the gas itself is the “slow guy” limiting the rate of gas exchange).
What is the equation that involves pulmonary vascular resistance (PVR) that can tell you about all the causes of pulmonary HTN? (Hint: starts with Ppa, or pressure of pulmonary arteries, equals…)
Ppa= CO * PVR + Pla
(Pressure of pulmonary arteries = cardiac output * pulm vascular resistance + pressure in LA)
*if Ppa is high that means pulmonary HTN, and can be due to any of the other variables being high.
How do you calculate A-a gradient? What does it mean conceptually? What is a normal A-a gradient value?
A-a= P(A)O2 - P(a)O2
(Oxygen in Alveoli - oxygen in arteriole/ capillary)
Tells you about how well oxygen is diffusing across from the alveoli to the capillary in gas exchange. Normal= 10-15mmHg (for example, oxygen in Alveoli= 100. Oxygen in capillary= 90 bc there is a little blood that normally flows past w/o getting oxygenated. A-a= 100-90= 10= normal. If A-a were high (>15) you’d know air is having a hard time diffusing across the alveoli and interstitium to get to capillary—> hypoxemia (low oxygen in blood))
Why is TB most often seen in the apex of the lungs (vs. the base of the lungs)?
The apex of the lungs has the highest V/Q ratio. That means the most oxygen is available at the apex and TB likes that.
Where in the lungs (apex, middle, or base) is ventilation (V) highest? Perfusion (Q)? V/Q ratio?
Highest V and Q at the base of the lungs (think of it as more oxygen and blood will go there due to gravity). Highest V/Q ratio at apex of lungs (due to small V/ smaller Q= bigger ratio) so more oxygen is available for gas exchange at the top of the lungs (*this is why organisms like TB thrive at the apex- they like oxygen).
What is a shunt? Dead space?
Shunt= perfusion w/o ventilation (complete blockage of ventilation through alveoli). V/Q= 0/#= 0.
Dead space= ventilation w/o perfusion (blood flow blockage). V/Q= #/0= infinity.
What 2 criteria are needed to rule out obstructive lung dz?
FEV1/FEV ratio > 0.7 AND FVC is normal (not reduced)
*for the purposes of board exams, if FEV1/FEV is <0.8 it’s obstructive. If >0.8 it’s restrictive.
In very general terms, what is the difference between obstructive and restrictive lung disease?
Restrictive= problem getting air in/ inhaling (alveoli problem, like in fibrosis) “too small of a cup” Obstructive= problem getting air out/ exhaling (airway problem, like in COPD, chronic bronchitis, asthma) “too narrow of a straw to slurp up that milkshake”
Do you see increased, normal, or decreased RV, FRC, and TLC in obstructive lung dz? How about restrictive lung dz?
(RV= vol left in lungs no matter how hard you blow out, FRC= vol air in lungs after breathing out normal, TLC= vol of air in lungs after max inspiration, or sum of all lung volumes)
Obstructive (problem getting air out)—> increased RV, FRC, TLC (air trapped)
Restrictive (problem getting air in)—> decreased RV, FRC, TLC (less air left behind in lungs bc you breathe in less air to begin with)
What’s a normal FEV1/FEV ratio?
0.8 (80%)
Though some textbooks may say 0.7
What is FEV1 and FEV (conceptually)? What happens to those values (increase, stay same, or decrease) and to the FEV1/FEV ratio in restrictive lung dz? Obstructive lung dz?
FEV1 (fraction expired volume in 1 sec.)= max air you can blow out in 1 sec.
This is decreased in restrictive (problem getting air in= less air in= less air out) but decreased more in obstructive (problem getting air out, and they have the hardest time getting air out initially).
FEV (fraction expired volume)= max air you can blow out after max inspiration.
This is decreased in restrictive (problem getting air in= less air in= less air out) and decreased equally in obstructive (problem getting air out).
FEV1/FEV is normal or increased in restrictive (problem getting air in and dec FEV1/ dec FEV= normal.
FEV1/FEV is decreased in obstructive (problem getting air out and really dec FEV1/ dec FEV= dec ratio) (**But, it is possible to have inc ratio in obstructive disease if FEV is even lower than FEV1…this is why to rule out obstructive disease you must have both a big ratio of FEV1/FEV> 0.8 AND a normal, not lowered, FVC—learned in first year, but not important for board exams)
What is the atopic triad?
Allergic rhinitis, asthma, eczema
A kid has allergic rhinitis and eczema. What 3rd condition is the kid likely to have?
Asthma. Atopic triad= allergic rhinitis + asthma + eczema (3 allergy conditions that often go together)
What is rhinitis and what’s the most common cause of it?
Common cold. Rhinovirus.
Kid with nasal polyp. What should you test the kid for?
Cystic fibrosis (note: nasal polyps form from repeated bouts of rhinitis= inflammation of the nasal mucosa, or the common cold)
What are the 2 causes of nasal polyps (in Pathoma)?
Cystic fibrosis and aspirin- intolerant asthma (note: nasal polyps form from repeated bouts of rhinitis= inflammation of the nasal mucosa, or the common cold)
What is the triad seen in aspirin-induced asthma?
(1) asthma (2) aspirin-induced bronchospasms (3) nasal polyps (seen in 10% of asthmatic adults)
* think of it like asthmatics that are allergic to aspirin/ don’t tolerate it well (the nasal polyps form from repeated bouts of rhinitis= inflammation of the nasal mucosa, or the common cold)
Adolescent male with non-stop nosebleeds. What are you thinking of?
Angiofibroma (benign nasal tumor of the blood vessel)
African kid or Chinese adult with history of EBV. Presents with swollen cervical lymph nodes and mass in the nasopharynx. Biopsy reveals pleomorphic keratin-positive cells. What is the most likely diagnosis?
Nasopharyngeal carcinoma (note: keratin-positive means Epithelial cells and carcinoma= cancer arising from epithelial cells)
What’s the most common cause of acute epiglottitis?
H. Influenza type B (vaccinated kids can get it too bc vaccines aren’t perfect, but usually will see it in an un-vaccinated child)
What does carcinoma mean?
Malignant cancer arising from Epithelial cells
Kid comes in with fever, sore throat, drooling, muffled “hot potato” voice, and inspiratory Stridor. What’s the most likely diagnosis?
Acute epiglottitis (from H. Flu type B) (Symptoms are from larynx inflammation and airway obstruction)
Kid with barking cough and inspiratory stridor. What is it?
Laryngotracheobronchitis, or Croup. Most likely from parainfluenza virus. (Note: inspiratory stridor is due to inflammation blocking the large airways)
A singer presents with hoarseness to the voice and a nodule on her true vocal chord. What is the most likely diagnosis?
Vocal chord nodule, or “signer’s nodule” (due to overuse of vocal chords, made of connective tissue, resolves with resting of the voice)
Kid presents with hoarseness and benign growth (finger-like projection) on the vocal chord. What cell type are you most likely to see on histology?
Koilocytes. This is a laryngeal papilloma due to HPV 6 and 11.
Kid presents with benign growth of the vocal chord. What virus is associated with this?
This is a laryngeal papilloma. Answer= HPV 6 and 11.
What is the difference between laryngeal papilloma and laryngeal carcinoma? What are the risk factors/ what brings it on?
Laryngeal papilloma= benign tumor, projection off of the vocal chord. Associated with HPV 6 and 11.
Laryngeal carcinoma= squamous cell carcinoma arising from the epithelial lining of the vocal chord. Risk factors= alcohol and tobacco (inc risk for pretty much any throat/ mouth CA due to the chronic inflammation they cause).
What’s the difference between the pneumonia types: lobar pneumonia, bronchopneumonia, and interstitial/ atypical pneumonia?
LOBAR PNEUMONIA- consolidation (fluid) of an entire lobe
BRONCHOPNEUMONIA- consolidation around bronchioles (small airways) (patchy)
INTERSTITIAL (ATYPICAL) PNEUMONIA- no consolidation but inflammation is in the interstitium (you’d see increased lung markings on X-ray)
What’s the most common cause of community-acquired pneumonia? What’s the most common cause of secondary pneumonia (you get a viral infection and then pneumonia)?
Most common cause of pneumonia- STREP PNEUMO.!
Most common cause of secondary pneumonia- still STREP PNEUMO. 2nd most common secondary pneumonia is STAPH AUREUS.
What are the 4 gross phases of lobar pneumonia?
(1) congestion (inflammation of vessels and edema)
(2) red hepatization (lung takes on a solid liver-like look rather than its normal spongy look—this is due to exudate, inflammatory cells, and blood from the leaky inc vascular permeability vessels)
(3) gray hepatization (cells die)
(4) resolution (the lung heals by type II pneumocytes acting as stem cells to regenerate the alveolar lining)
Patchy consolidation around bronchioles. What kind of pneumonia are we talking?
Bronchopneumonia
What category of pneumonia is characterized by diffuse interstitial infiltrates?
Interstitial (atypical) pneumonia
Fever. Chills. Productive cough with yellow-green sputum (pus) or rusty (blood) sputum. Tachypnea (rapid, shallow breathing) with pleuritic chest pain. Dullness to percussion. Elevated WBC count. What are you thinking (general diagnosis)? Explain these symptoms/ findings.
Pneumonia (infection of the lung parenchyma= functional part of the lungs). Occurs when normal defenses are impaired (impaired cough reflex, damage to mucociliary escalator, mucus plugging). The infection causes cough bc that’s your body’s reflex to get the bacteria/ organism causing it out of there. You get pleuritic chest pain bc bradykinin and PG E2 are inflammatory mediators released and you are stretching out the lungs when you breathe in. Dullness to percussion indicates fluid/ consolidation.
How do we diagnosis pneumonia besides history and physical exam? (in other words, what tests do we get)
Chest X-ray, sputum gram stain and culture, and blood cultures (organisms are often in the blood)
Why does diabetes increase one’s risk for developing Klebsiella pneumoniae and all infections in general?
Diabetes= inc sugar in blood. Bacteria thrive on that sugar.
Alcoholic in a nursing home has a nasty cough going on and is coughing up thick, currant jelly sputum. What are you thinking?
Klebsiella pneumoniae.
Why are alcoholics at increased risk for Klebsiella pneumoniae?
You get it from aspirating enteric (GI) flora. For example, you vomit and breathe that up. Alcoholics vomit more and are more likely to choke on their own vomit while intoxicated.
Why are you at increased risk for getting a bacteria pneumonia (like strep pneumo or staph a.) following the flu (or right after any kind of viral infection)?
The virus knocks out the mucociliary escalator (part of your defense for pushing bad stuff out of the body)—> you become more susceptible to bacteria without this defense.
What 3 types of pneumonia are more often seen in COPD patients (leads to exacerbation of COPD)?
H. Flu, moraxella, and legionella
Pneumonia + diarrhea. What are you thinking?
Legionella! (Other hints: community-acquired pneumonia, smokers, water heaters, silver staining, not seen on normal gram stain)
What type of pneumonia is common among Cystic Fibrosis patients?
Pseudomonas aeruginosa
What’s the most common type of atypical/ interstitial pneumonia?
Mycoplasma penumoniae